A variety of user interface devices have been developed to help users interact with electronic devices, such as computers, personal data assistants (PDAs), cell phones, global positioning units (GPSs), etc. A mouse is probably to most common of these interfaces. A mouse often includes a track ball or optical sensor to detect motion over a surface. Hardware and/or software can capture the sensor input and translate the motion to an image on a display. For example, with a mouse, a user may be able to move a cursor or pointer, “click-and-drag” an icon or graphical representation of an object, move about in a virtual environment, etc. In each of these cases, however, motion is usually constrained to just two degrees of freedom at a time. That is, a mouse can usually only capture motion in two directions over a surface.